HEAVY METALS DISTRIBUTION IN GRADO HEAVY METALS DISTRIBUTION IN GRADO
LAGOON SEDIMENTS LAGOON SEDIMENTS
Bottos
Bottos D* D*, Mao A, Manente S, De , Mao A, Manente S, De Pieri Pieri S, Perin G** S, Perin G**
Department of Environmental Sciences, Ca’ Foscari University of Venice Dorsoduro 2137, 30123 - Venice (Italy)
*[email protected] **[email protected] ABSTRACT
ABSTRACT Grado lagoon is the eastern part of the larger Marano and Grado transition environment, located in the North Adriatic Sea (Italy).
Besides agricultural, fish and mussel farming activities, many industrial activities stand on this sensitive ecosystem, like plant producing cellulose and chlor-alkali, textile industries, steel plants, metallurgical industries.
17 samples of surface sediments were collected and the concentrations of heavy metals (Cd, Cu, Cr, Hg, Ni, Pb, V) were determined by acid microwave digestion. The lowest values of metals concentrations has been found in sediment sampled close to lagoon’s inlets where the effect of sea water exchange is higher.
On the other hand, seven sample points, set in the inner part of lagoon characterized by deposition phenomena, show the higher metals concentration values. Moreover, the high concentrations of Hg and Ni in whole of sites, point out a probable anthropogenic source. A very strong correlation between concentrations of Ni and V (R
2= 0,99) and between Ni and Pb (0,83) was found;
Further studies should be carried out in order to assess the relationship between anthropogenic activities and sediment quality.
9
9 17 sediment samples have been collected (FIG. 1), homogenized an 17 sediment samples have been collected (FIG. 1), homogenized and stored at 4 d stored at 4 ° °C , in the dark, until analysis. C , in the dark, until analysis.
9 9 Sediment has been digested using microwave digester (ETHOS 1600) Sediment has been digested using microwave digester (ETHOS 1600) with 5 mL of milliQ with 5 mL of milliQ water, 1,5 mL of Hydrofluoric Acid (Riedel de water, 1,5 mL of Hydrofluoric Acid (Riedel de Ha Haë ën n, Germany) and 3 mL of , Germany) and 3 mL of Acqua Acqua Regia Regia (3:1 HCl:HNO (3:1 HCl:HNO
33, , J.T. Baker J.T. Baker Instra Instra Analized Analized, U.S.A.). , U.S.A.).
9
9 Samples have been analyzed by ICP Samples have been analyzed by ICP- -MS. MS.
0 4 8 12 16 20 24 28 32 36 40 44 48 52 56
13.04 13.0613.08 13.1 13.1213.1413.16 13.18 13.2 13.2213.2413.26 45.4
45.42 45.44 45.46
3 4
5
2 6 7 9
8
10 11 13
12 14 15 1617
1
Nickel
Ecotoxicology Ecotoxicology
IN TR ODUCTI ON IN TR ODUCTI ON MA TE RI A LS & ME TH O D S MA TE RI A LS & ME TH O D S RE SU LTS & DI SC US SI O N RE SU LTS & DI SC US SI O N CON C LU SI O N S CON C LU SI O N S
References References
Brambati A (1996). Metalli pesanti nelle lagune di Marano e Grado. Regione Autonoma Friuli- Venezia Giulia, Servizio dell’Idraulica, Trieste.
Piani R, Covelli S, Biester H (2005). Mercury contamination in Marano Lagoon (Northern Adriatic sea, Italy): Source identification by analyses of Hg phases. Applied Geochemistry, In Press.
Theofanis Z, Schmidt A, Grigorova L, Calmano W (2001). Contaminants in sediments:
remobilization and demobilisation. The Science of the Total Environment 266:195-202.
sand clay
silt
sand-clay GRADOGRADO
LIGNANO LIGNANO
AQUILEIA AQUILEIA MARANO
MARANO
FIG. 2– Sediments granulometric distribution (modified from Brambati, 1996)
Sediments are repositories for physical and biological debris Sediments are repositories for physical and biological debris and sinks for a wide variety of chemicals (
and sinks for a wide variety of chemicals (Theofanis Theofanis, 2001), , 2001), coming from freshwater rivers, air, marine pollution, etc.
coming from freshwater rivers, air, marine pollution, etc.
Sediments are the sinking device for pollutants but also could Sediments are the sinking device for pollutants but also could be a dangerous point of release of contaminants.
be a dangerous point of release of contaminants.
FIG. 3 – Concentrations of metals in sediment samples:
↑
↑ graph AVanadium, Nickel, Chrome, Lead and Copper Vanadium, Nickel, Chrome, Lead and Copper
←
← graph BMercury and CadmiumMercury and Cadmium
Cd, Cu and Pb concentrations are low in all sediment samples (FIG. 3 graph A – graph B).
Hg concentrations are very high in all the sediment samples: the values are over 2* µg g
-1d.w. except three samples; in five stations the value exceeds 5 µg g
-1d.w. and only in two samples it’s below 0,5* µg g
-1d.w.
* “Protocollo Venezia” (Law n. 360/1991)
13.04 13.06 13.08 13.1 13.12 13.14 13.16 13.18 13.2 13.22 13.24 13.26 45.4
45.45
3 4
5
2 6 7 9
8
10 11 13
12 14 15 16 17
1
FIG. 1
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5
13.0413.06 13.08 13.1 13.1213.1413.1613.1813.2 13.2213.2413.26 45.4
45.42 45.44 45.46
3 4
5
2 6 7 9
8
10 11 13
12 14 15 1617
1
Mercury
Interpolation of Hg and Ni concentrations Interpolation of Hg and Ni concentrations
in surface sediment.
in surface sediment.
Ni vs metals
R2 = 0,8334 R2 = 0,9913
R2 = 0,9401
0 10 20 30 40 50 60 70 80
0 10 20 30 40 50 60
Ni (µg g-1) V - Cu - Pb (g g-1)
Pb V Cu
FIG. 5
Sample points with high concentrations of metals in sediment are localized in the inner part of the lagoon, characterized by deposition phenomena and fine granulometry (silt and clay) (FIGs 2, 3 and 4).
Areas of greater metals accumulation coincide with areas of sediment deposition.
Almost of all metals distribution maps show a similar distribution; Hg and Ni maps have been here reported (FIG. 4).
Strong correlations exist between Ni and V, Ni and Cu, Ni and Pb concentrations in surface sediment (FIG. 5). It could be an interesting information about anthropogenic activities as source of pollution (e.g. Ni and V are commonly used as alloying addition to iron and steel).
Metals
0 1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Samples µg g-1 d.w.
Hg Cd
graph graphBB
Metals
0 10 20 30 40 50 60 70 80 90 100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Samples µg g-1 d.w.
V Ni Cr Pb Cu
graph graphAA
Source of pollution affecting Source of pollution affecting Grado Grado Lagoon are various industrial activities Lagoon are various industrial activities like steel plants, metallurgical industries, like steel plants, metallurgical industries, a plant producing cellulose and a plant producing cellulose and chlor chlor- - alkali. Besides agricultural, fish and alkali. Besides agricultural, fish and mussel farming activities stand on the mussel farming activities stand on the basin.
basin.
Sediment samples n° 10, 16 show the lowest concentrations for all the metals investigated, while samples n° 6, 8, 12, 13 show the highest values.
Sample points with low concentration of metals in the sediment are the closest to lagoon inlets, where the ingression of sea water is strong and the sediments are
predominantly sandy (FIGs 2 and 3).
Nickel Nickel Mercury Mercury FIG. 4
Marano-Grado Lagoon, North Adriatic Sea (Italy)
Sampling area Sampling area
Piani Pianiet al., 2005et al., 2005
a
Inner areas of the basin, characterized by sediment deposition (silt and clay), and the zone influenced by Aussa-Corno river inputs are characterized by the greatest pollution.
a
The critical problem of Grado Lagoon is Mercury contamination of sediments. It has probably both natural and anthropic origin. Other studies (Piani et al., 2005) identified the presence of both cinnabar and non-cinnabar (usually the chemical form more mobile) compounds in Marano Lagoon (FIG. 1). The spatial distribution of non- cinnabar compounds results influenced by freshwater inputs, in particular Aussa-Corno river; it passes through Torviscosa industrial area where many activities, like chemical plants, are present. High values of Hg in the eastern part of the basin are more probably due to Isonzo river input, coming from Idrija (SLO), a cinnabar mining zone.
a
Further studies could be useful to clarify Ni vs V – Cu – Pb strong correlation.
Provincia di Gorizia Provincia di Gorizia -- Territory
Territoryand and EnvironmentalEnvironmental Office
Office
Acknowledgments Acknowledgments
SETAC EUROPE XVI Annual Meeting SETAC EUROPE XVI Annual Meeting
The Hague , 7
The Hague , 7 ––11 May 200611 May 2006 Sediment Ecotoxicology: from testing Sediment Ecotoxicology: from testing
methods to quality standards methods to quality standards
µg g-1d.w.
µg g-1d.w.
